Great Lakes nearly freeze over completely

But not Lake ontario

Great Lakes ice coverage

During a winter when ice coverage on the Great Lakes hit a high of 88 per cent, Lake Ontario manages to avoid the brunt of Old Man Winter.

Given the bone-chilling temperatures this winter, it may not come as a surprise that last week the Great Lakes almost completely froze over, reaching a high this winter of 88 per cent ice coverage.

The last time there was that much ice was two decades ago, when 90 per cent of the lakes froze.

But one lake is better at avoiding Old Man Winter’s frozen touch: Lake Ontario.

On Thursday, when ice levels hit their highest peaks this season, about 95 per cent of lakes Superior, Huron and Erie were covered in ice. And about 80 per cent of Lake Michigan, and 41 per cent of Lake Ontario were frozen, according to the U.S. government’s Great Lakes Environmental Research Laboratory (GLERL).

By Saturday evening, 81 per cent of the Great Lakes remained frozen — and just 25 per cent of Lake Ontario.

So why, in this chain of five freshwater lakes, is Lake Ontario so different?

“Yeah, of all the lakes, it is a very strange lake,” laughs Jia Wang, an ice climatologist at GLERL, located in Ann Arbor, Mich.

It’s one of the more interesting lakes to study, he says, especially in what has been “a very, very interesting year.”

Among the key reasons why Lake Ontario hasn’t frozen to the same extent as the others has to do with its depth and location.

Although it’s the smallest of the Great Lakes, with a surface area of about 19,000 square kilometres, it is the second deepest, with an average depth of 85 metres.

“Depth is a big issue because the deeper the water, the more heat it can receive and store,” said Wang. “Even though Superior is deeper than Ontario the water temperature there is much lower.”

Lake Superior has an average depth of 148 metres, which enables it to also absorb heat. But being the most northwest of the Great Lakes means that even its deep waters are no match for the freezing effects of cold Arctic fronts, says Wang.

Because those cold fronts usually come down from the northwest, and Lake Ontario is the farthest east of the Great Lakes, it ends up getting less cold air than the others, notes Wang.

David Phillips, Environment Canada’s senior climatologist, says the waters flowing into Lake Ontario — it is the downstream Great Lake — may be a factor in why it’s not freezing like the others.

The flow of the Niagara River, which connects lakes Erie and Ontario, “would help to circulate the water and prevent the ice from forming because there’s more agitation,” says Phillips.

“But certainly, we know that all of the waters from lakes Superior, Michigan, Huron and Erie are flowing into Lake Ontario and that would be another factor that would keep it, perhaps, a little less likely to form ice.”

Less ice coverage on Lake Ontario means the open water may result in more lake effect snow in areas such as Kingston, says Phillips.

What’s happening this year isn’t unusual, says Wang. In 1994, when 90 per cent of the Great Lakes were frozen, just 55 per cent of Lake Ontario was ice.

The highest ever recorded ice coverage, says Wang, was in 1979 when 94 per cent of the Great Lakes froze, and 85 per cent of Lake Ontario.

Phillips, however, says anecdotal evidence suggests that Lake Ontario froze completely during the winters of 1892-93 and 1933-34.

“In 1933-34, people actually went skating on Lake Ontario,” he said. “They would head out and skate and skate as far as they could go and then they’d come back.”